Method for the filtration of a bioreactor liquid from a bioreactor; cross-flow membrane module, and bioreactor membrane system

Abstract

The invention provides a method for the filtration of a bioreactor liquid ( 10 ) from a bioreactor ( 1 ) with a cross-flow membrane module ( 20 ) comprising one or more membranes ( 40 ). The method comprises feeding part of the bioreactor liquid ( 10 ) to a liquid inlet ( 21 ) of the cross-flow membrane module ( 20 ), transporting the bioreactor liquid ( 10 ) through the cross-flow membrane module ( 20 ) in a cross-flow mode, and removing a retentate ( 12 ) from a liquid outlet ( 22 ) of the cross-flow membrane module ( 20 ). The cross-flow membrane module ( 20 ) is arranged to allow a liquid downward flow of the bioreactor liquid ( 10 ) through the cross-flow membrane module ( 20 ). The method further comprises providing the liquid downward flow and a downward gas flow of a gas ( 30 ) through the cross-flow membrane module ( 20 ). Fouling of the membranes is relatively good prevented or reduced in time. Further, the liquid flow may be reduced relative to conventional configurations.

1 . A method for the filtration of a bioreactor liquid from a bioreactor with a cross-flow membrane module ( 20 ) comprising one or more membranes, wherein the method comprises:
 a. feeding the bioreactor liquid or part thereof to a liquid inlet of the cross-flow membrane module,   b. transporting the bioreactor liquid through the cross-flow membrane module in a cross-flow mode, and   c. removing a retentate from a liquid outlet of the cross-flow membrane module,   wherein the cross-flow membrane module is arranged to allow a liquid downward flow of the bioreactor liquid through the cross-flow membrane module, and wherein the method further comprises providing said liquid downward flow of the bioreactor liquid and a downward gas flow of a gas through the cross-flow membrane module.   
     
     
         2 . The method according to  claim 1 , wherein the gas holdup in the liquid downward flow through the cross-flow membrane module is in the range of 5-25 vol. %. 
     
     
         3 . The method according to  claim 1 , wherein the liquid downward flow has a superficial liquid flow velocity in the range of 0.2-1.5 m/s. 
     
     
         4 . The method according to  claim 1 , wherein the bioreactor liquid and the gas are mixed before flowing through the cross-flow membrane module in a cross-flow mode. 
     
     
         5 . The method according to  claim 1 , wherein a retentate of the cross-flow membrane module is fed to the bioreactor 
     
     
         6 . The method according to  claim 1 , wherein the one or more membranes comprise one or more tubular membranes, arranged to allow the liquid downward flow of the bioreactor liquid and the downward gas flow of the gas through the one or more tubular membranes in a cross-flow mode. 
     
     
         7 . The method according to  claim 1 , wherein the gas comprises one or more of air and biogas. 
     
     
         8 . A cross-flow membrane module comprising one or more membranes, a liquid inlet for a bioreactor liquid and a liquid outlet for a retentate of the cross-flow membrane module, wherein the cross-flow membrane module further comprises a gas inlet for a gas, and wherein the cross-flow membrane module, the liquid inlet, the liquid outlet, and the gas inlet are arranged to allow a liquid downward flow of the bioreactor liquid and a downward gas flow of the gas through the cross-flow membrane module in a cross-flow mode. 
     
     
         9 . A membrane bioreactor system comprising a bioreactor and a cross-flow membrane module according to  claim 8 , arranged external from the bioreactor, wherein the bioreactor is arranged to comprise a bioreactor liquid, and wherein the bioreactor is in liquid communication with the liquid inlet of the cross-flow membrane module. 
     
     
         10 . The membrane bioreactor system, wherein the bioreactor is in liquid communication with the liquid outlet of the cross-flow membrane module, and wherein the membrane bioreactor system is arranged to circulate at least part of the bioreactor liquid through the cross-flow membrane module. 
     
     
         11 - 12 . (canceled)